Holddown clamp



y 5, 1953 E. G. CLARK 2,637,226

HOLDDOWN CLAMP Filed Nov. 7, 1950 2 SHEETSSHEET 1 I N VEN TOR.

g 2- BY Edward 6. Clark ATTORNEY E. G. CLARK HOLDDOWN CLAMP May 5, 1953 2 SHEETSSHEET 2 Filed NOV. 7, 1950 IN VEN TOR. Edward 6. Clqrk WFffM AT TORNEY Patented May 5, 1953 UNITED STATES PATENT E F I C E 2 Claims. (01. 77-63) (Granted under Title 35, U. S. Code (1952),

see. 266) The invention described herein may be manufactured and used by or for the Government of the United States for governmental purposes without the payment to me of any royalty thereon in accordance with the provisions of the act of March 3, 1883, as amended (45 Stat. 467; 35 U. S. C. 45).

This invention relates to clamping devices and more particularly to clamping devices adapted for use with drill presses and the like for the purpose of clamping work pieces into position to be worked on.

The principal object of the invention is to provide a device which is simple in construction and operation, highly flexible in use with a Wide range of configurations and sizes of work, very rapid in operation and at the same time capable of exerting sufficient clamping force to insure complete safety from the danger of slipping.

Another object of the invention is to provide a novel clamping or work-holding device which may be readily mounted on the column of a drill press or on an equivalent element so as to be quickly adjustable thereon linearly or r'otatively Without major adjustment to the size of the work.

Other objects and advantages will appear from the description below with the aid of the attached drawings, in which:

Figure 1 is a side elevation of a drill press with a clamp according to my invention attached thereto.

Figure 2 is a sectional plan View taken on line 22 of Figure 1.

Figure 3 is a perspective view showing my invention utilized to hold a small flanged work piece.

Figures 4 and 5 are detail views showin different forms of work-holding feet used with my invention.

Figure 1 shows a conventional type of drill press having a base I with a cylindrical column 2 rising therefrom and supporting at its upper end the drill press head assembly 3 in which the toolsupporting spindle 4 is axially movable. A work table 5 is supported by the collar 1 so as to be vertically adjustable on column 2 in the usual fashion.

My improved adjustment comprises an adjustable collar 8 supporting a pair of arms I and I", one of which is fixed relative to collar 8, while the other is swivelly mounted with respect to the collar, as indicated at l I (Figure 2). An extensible arm 9 is coupled to the arm l so as to allow the arm 9 to be moved nearer to or farther from the column 2. This arm is enlarged as shown at and 25 so that a hole,'1arge enough to receive arm [5, may be provided in the enlarged section in the horizontal plane parallel to arm .i'he arm I5 passes through this hole and therefore the arm 9 may be moved to any desired position with respect to the column 2 within the limits set by the length of arm it. The two arms are clamped in the desired position by means or" the turn screw 30. As arms 9 and iii are otherwise identical and carry similar clamping elements at their ends, only one of these will be described. The extremity of each arm is equipped with a plunger-type toggle clamp as indicated at it, having a linkage as shown at it, which is operated by handle l4, shown in the closed position in Figure 3, and in the open position in Figure 1. The operating plunger Iii of the toggle clamp is internally threaded to accommodate the spindle and foot assembly ll. The hold-down foot of this assembly may be of various types such as swivel foot. inverted V for holding cylindrical work, neoprene cushion foot for holding work having soft or polished surfaces to avoid marring, or special positioning fixtures as indicated by Figures 3, 4, and 5, respectively.

An arm 15 may be rigidly attached to the clamping collar, as is shown in the case of arm [5, or may be hinged thereto as shown in it. The arrangement with. one arm rigid and one arm hinged appears to aficrd the greatest utility, since it permits a reasonable amount of flexibility with a minimum complication of elements. The range and flexibility of the clamping device may be still further increased by incorporating in both arms the slide arrangement shown with respect to arm In operation the clamping unit is swung over the machine table and initial vertical adjustment made by tightening the clamping collar 8 at the machine column. Further adjustment may be made by turning the threaded spindle H in or out of the operating plunger of the toggle clamp [6. The clamping unit may be swung clear of the machine table if desired, without removal from the machine, to facilitate movement of work in and out of the machine or to perform operations that do not require clamping. This may be accomplished in a matter of seconds, since the fixture, being attached to the machine, is always available.

Another use of my invention is as a locating fixture or to hold a locating fixture. For example, when a series of equally-spaced holes is to be drilled, a pointed spindle may be used in the operating plunger of the clamp to engage the 3 drilled hole and locate it in relation to the drill spindle for the succeeding hole.

While the foregoing description sets forth certain specific details and structure, it will be understood that these are by way of example, and that such details and structure may be varied by those skilled in the art without departing from the spirit of the invention as defined in the anpended claims.

I claim:

1. A work-holding attachment for a drill press or the like having a work-supporting table and a column perpendicular to said table, comprising a clamping collar having means for adjustably clamping same to said column, an arm extending from said clamping collar adjacent to the working surface of the work-supporting table, a second arm extending from said clamping collar adjacent to the working surface of the work-supporting table, said second arm including pin mean for mounting said second arm to said collar thereby allowing the said second arm to move in a horizontal plane with respect to said collar, a toggle clamp carried at the end of each of said arms, each of said clamps having a plunger moving toward and away from the said work table and handle, a quick-acting irreversible mechanical linkage for controlling the motion of each of said plungers toward and away from said work table, said plungers being formed of hollow cylinders the insides of which are screw threaded and work-engaging hold-down feet mounted on cylindrical shafts said shafts having external screw threads for engaging the said screw threads inside of said hollow plungers.

2. The invention according to claim 1, said first arm being extensible, and means for clamping said arm in any extended position thereof.

EDWARD G. CLARK.

References Cited in the file of this patent UNITED STATES PATENTS Number 

